[RE-wrenches] EG4 v HomeGrid battery systems update?

Wed Sep 3 14:12:11 PDT 2025

This brings me back to a question I was trying to get data on…

Not just specific to HomeGrid, but what Inverter was being used in this case? Was it open loop or closed loop? If open loop, was it inverter driven % based or  inverter driven Voltage based?

Recently, I had a long intermittent technical issue with a pair of Sol-Ark inverters that was using open loop but percentage based and it kept crashing out because the Simpliphi Battery BMS was at zero SOC when the inverter thought there was something left.

I added a Victron SmartShunt to monitor and found that Inverter Percentage was not charging to the proper voltage (high enough to fill all the batteries). I switched to Voltage control and now all is well. Even the chart data on the inverter would show low voltage situations and would explain the situation. I just hadn’t even looked at the data deeply enough.

I wonder if Percent Closed Loop control is better than Percent Open Loop control or are we leaving energy on the table?

Let me know what you think?

Maverick

Maverick Brown
Off-Grid Solar Commander since 2006
Maverick Solar Enterprises, Inc.
 • Solar Commander Remote Power
 • SunFlow Systems Cathodic Protection 
maverick at mavericksolar.com
512-460-9825

> On Sep 3, 2025, at 3:55 PM, Ray Walters via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
> 
> I have one Home Grid system out here; its in their outdoor enclosure with built in battery heating.  I've had more call backs in the past year with that system than all my other off grid systems combined.  I've struggled with getting the right LVD settings, and even with decent settings, it seems the battery heating and the no load draw of the BMS will go ahead and drag the battery into shut down, requiring a trip out.  I have a small variable DC power supply which has been very important in the new days of LiPO4.  I run it on a Ryobi inverter.  
> 
> One of the times I went out, the system was not shut down, but the HomeGrid screen was blank, and I had to reboot the battery to get it back on.  I also experienced the BMS shutdown others mentioned, when one of the 4 batteries was out of EQ with the other batteries.  Even the initial startup was a nightmare, requiring a tech to take over my computer remotely, and then a month later, I had to sit out there for 3 hours while it came to full charge so I could bring the 4th battery back on line.  At least their Tech Support was really good.
> 
> Also their outdoor enclosure is really chinzy, it takes over 30 stainless screws to attach the 2 halves together, and many of those screws have galled  and are unusable.  I even had to cut a couple off just to get in to service the battery.  
> 
> Ray
> Remote Solar
> 
> On 9/3/2025 11:18 AM, Jason Szumlanski via RE-wrenches wrote:
>> Nothing like a coincidence... 
>> 
>> A client on an island with three stacks of 8 HomeGrid batteries has just called me to report that the entire system is down. All of the battery BMS module displays are dark. I have mySolArk data from three inverters there that show the batteries were topped off and just idling along with solar covering the load at 5:00 pm last night when the power suddenly went out, killing the Starlink connection. I'm going for a boat ride tomorrow to check it out. Ugh. 
>> 
>> I will report my findings. Not sure if it's a battery or inverter issue, but the customer's handyman reported nothing on the battery screens, which seems strange to me. Even an error should not turn the display off, as far as I recall.
>> 
>> P.S. No power loss notifications from Sol-Ark is a frustrating loss of functionality. I heard a rumor on Facebook that they are fixing this in mySolArk this month, but I'm not holding my breath.
>> 
>> 
>> Jason Szumlanski
>> Principal Solar Designer | Florida Solar Design Group
>> NABCEP Certified Solar Professional (PVIP)
>> Florida State Certified Solar Contractor CVC56956
>> Florida Certified Electrical Contractor EC13013208
>> 
>> 
>> On Tue, Sep 2, 2025 at 4:31 PM Jason Szumlanski <jason at floridasolardesigngroup.com <mailto:jason at floridasolardesigngroup.com>> wrote:
>>> We have some stacks of HomeGrid out there in various capacities, from the smallest with five in a stack, up to four fully populated stacks of eight. In total, I oversee around 150 Stack'd batteries, including many that I installed and some that were installed by others. I will say that they are easy to install, have a nice bold visual interface, look good, and perform up to expectations. They communicate flawlessly with Sol-Ark 15k. However...
>>> 
>>> I believe there is a fundamental design flaw in this stackable battery architecture. Here is why I am no longer offering HomeGrid in a nutshell:
>>> When one battery in a stack has a fault, the entire stack faults out, which renders the stack non-functional until you either:
>>> Remove the battery from the stack or turn the circuit breaker off, and:
>>> Reconfigure all of the dip switches to remove the battery from the communication loop, then:
>>> Reprogram the master BMS to recognize the new stack members and their positions.
>>> If you have multiple stacks, you have to do all of the above, and in addition:
>>> Remove a battery from each additional stack to balance them, then perform all of the above steps on each stack. 
>>> But before you reprogram each master BMS you have to take the stacks out of parallel communication, then reprogram the parallel stacks before operation again. 
>>> Making each stack equal is per HomeGrid support, but in practice, I don't know if it is necessary, especially if you are losing one of eight (12.5%). If you have smaller stacks, this might be a bigger issue.
>>> To diagnose a battery issue with a laptop and cable and get warranty support, you can only do that with the master BMS because each battery does not have a comm port. That means you have to have the entire stack non-functional while you perform diagnostics, which is not ideal for off-grid settings, especially if there is only one stack.
>>> If a battery fails to balance and becomes depleted, causing a fault, there are no simple terminal bolts to connect an external charger. I'm not sure how you would even accomplish a manual charge without opening up the case.
>>> The EG4 server rack batteries work in a fundamentally different way. Each battery has an independent BMS. When there is an alarm in a stack or stacks of batteries, the entire battery bank does not fault out. You can physically take a battery out of the stack without changing any dip switches on the other batteries. You can shut one down or experience a fault on one battery without any others shutting down. I have tried this with the LifePower4 batteries, even when there are multiple communication strings of 16 batteries connected to a communication hub. The rest of the batteries just keep on working, which is the way it should be! The communication hub will just show zero values for the battery that is missing from the stack. I cannot confirm if this is the case with the LL batteries, but I suspect it would be. In a way, this is like having the batteries in an open loop in terms of resilience, with all of the benefits that closed-loop battery communications offers. I have had a small variety of battery issues with EG4, and not once has the whole bank of batteries been affected by one battery's issue.
>>> 
>>> Side note about another server rack option: I can confirm that Pytes Ebox V1 batteries in a communication stack will shut down all batteries if one has a fault, at least confirmed by one situation I had. This is despite each battery having it's own BMS and console port to communicate with the batteries. The situation in my case was a battery that had no "Barcode" programmed into it, which was causing a parallel communication fault and shutting down the whole stack. In this case, physically bypassing the battery with the issue with a Cat5 coupling worked fine. There are no dip switches to set, and the master battery reconfigures the communication stack automatically. With Pytes' support, I was able to manually code in the Barcode to the BMS with a console cable, and the problem went away. I am not sure if all varieties of faults would have the same effect with Pytes EBoxes, but this communication issue definitely caused the whole stack to fault out.
>>> 
>>> 
>>> The phenomenon of the new breed of LFP batteries lacking reliability/redundancy inspired a blog post that I did just a couple of weeks ago: https://floridasolardesigngroup.com/homegrid-stackd-batteries-the-redundancy-fallacy
>>> 
>>> 
>>> A couple of other notes on HomeGrid:
>>> They do not have any way to connect conduit to the BMS. You wouldn't want to anyway, especially with rigid conduit, since you might need to remove the BMS for service. The BMS should be at the bottom, in my opinion, for this reason. You can only run positive and negative battery cables out of the provided strain relief glands in free air, and it requires that the batteries be about 4 inches away from the wall. There is no suitable way to protect 100% of the battery cables.
>>> Along the same lines, if you ever plan to expand the system, make sure you leave enough battery cable length to reach a higher level.
>>> The lack of busbars is a really nice feature (until you get into larger systems).
>>> The discharge rate supports the maximum input for a Sol-Ark 15K with, I believe, just three batteries.
>>> I love their "busbar pair" designed specifically for the Sol-Ark 15K. I order a pair with every inverter, regardless of what battery I am using (although I am not actively selling Sol-Ark right now).
>>> You can't monitor the condition of individual batteries with Solar Assistant, or any other tool remotely to my knowledge. You can't even monitor the condition of paralleled stacks.
>>> The "app" for the batteries is mind-bendingly useless – unless I'm really missing something.
>>> For some firmware and hardware versions, over-the-air updates are not possible, and HomeGrid will need to send you an update tool. To be fair, I think this is also the case with EG4 and some other manufacturers.
>>> Once we received a shipment where three of eight batteries were in the right boxes, but there were no guts in the batteries at all! It was just an empty steel battery shell. We had to send them back to our supplier. The boxes actually said 13 Kg on the labels rather than 52 Kg, but nobody at the factory caught it. Strange.
>>> HomeGrid Support is very competent, I would say among the best in terms of knowing their products inside and out, but it's 50/50 whether I get someone on the phone or get a call back in a timely manner that allows me to complete a service call. They are willing to schedule assistance if you have an off-grid situation that requires help.
>>> 
>>> Is this a vote for EG4? Not necessarily, but it's hard to argue with the price and the superior reliability/redundancy aspects of the LifePower4/LL batteries. One battery fault should not shut down an entire system unless there is a legitimate safety hazard. It's possible that these are UL issues that require system shutdowns, but EG4 appears to have overcome the problems I've seen with other manufacturers' products.
>>> 
>>> Like others mentioned, I prefer to go with the 14.3 kWh / 16 kWh sealed batteries. I feel they have better build quality (other than my recent rant about rust on the MNP PowerFlo16), and keeping components sealed up better just makes sense to me, especially in challenging environments. Of course, if you want more modularity in terms of expansion options and less impact if a single unit goes down, 5 kWh units might be a better option. There is no right or wrong option, I guess – sometimes it just comes down to priorities, space, mounting options, and price. 
>>> 
>>> 
>>> Jason Szumlanski
>>> Principal Solar Designer | Florida Solar Design Group
>>> NABCEP Certified Solar Professional (PVIP)
>>> Florida State Certified Solar Contractor CVC56956
>>> Florida Certified Electrical Contractor EC13013208
>>> 
>>> 
>>> On Tue, Sep 2, 2025 at 10:41 AM Christopher Warfel via RE-wrenches <re-wrenches at lists.re-wrenches.org <mailto:re-wrenches at lists.re-wrenches.org>> wrote:
>>>> Hi Wrenches, I went through the archives and read the comparison between 
>>>> these two.  The HomeGrid manual was in such a mess (or my pdf reader was 
>>>> defunct), that I started looking at other options. If anyone has a 
>>>> strong opinion of either of these two, or something better, I would 
>>>> appreciate.  We traditionally install small systems, and this would be 
>>>> one (@15kWh).  I would prefer to use a racking system with the BMS as 
>>>> part of the packaging. Solark 12kPV multimode.  Thank you, Chris
>>>> 
>>>> -- 
>>>> Christopher Warfel, PE
>>>> ENTECH Engineering, Inc.
>>>> PO Box 871, Block Island, RI 02807
>>>> (401) 447-5773
>>>> 
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